/**
 * 
 */
package t4j.enumerated;

enum Signal{ GREEN,YELLOW,RED}

public class TrafficLight {
	Signal color = Signal.RED;
	
	//简化的状态模式
	public void change(){
		switch(color){
			case RED: 
				color = Signal.GREEN;
				break;
			case GREEN:
				color = Signal.YELLOW;
				break;
			case YELLOW:
				color = Signal.RED;
				break;
		}
	}
	
	@Override
	public String toString() {
		return "The traffic light is " + color;
	}
	
	public static void main(String[] args) {
		TrafficLight t = new TrafficLight();
		for(int i = 0 ; i < 7 ; i++){
			System.out.println(t);
			t.change();
		}	
	}
	
}
